TL;DR - Car has some problem, seems to be transmission, but keeps going away and coming back, pictures attached.

I have a 2010 Mazda3 i Touring Sedan with 79,000 miles on it, and during the snowstorm (I'm in Connecticut) somehow while driving my shield on the bottom of the car was hanging off of the car, and the car was shaking, which we later attributed to the shield.

Then, suddenly, my car dies in the middle of the road. I get it towed to Firestone, they say my Serpentine Belt snapped, and they replaced it.

The next day when I received my vehicle back, the air conditioning did not work. Then suddenly, the car felt like it was STOPPING on the highway, and the lights would flash.

I called a mechanic I know from my old hometown who owns a shop, and he took it in. He said the Transmission was fine, although the A/T light flashed when the car stopped suddenly while (I assume) changing gears.

The mechanic said I was missing another belt, fixed my A/C, fixed my Tire Sensor, and topped off my fluids. 2 days later the check engine light is now on, as well as other lights, and the car feels weird, idles weird, etc.

Does anyone have any idea what this could be? I have attached pictures as well.

ALSO - I should mention sometimes all the lights go off, and the car acts perfectly normal for up to 2-3 days so far. And when the lights A/T the car sliding, and the check engine light are on, the D for DRIVE and the other letters do not light up on the dash, all other lights work fine.